By actuator is meant a housing containing a plunger guided in it deplaceably against the force of the spring and ending on the outside in a part usually designated a pushbutton. The actuator can be attached to the support wall by, for example, clamping the support wall between a projection of the actuator housing and a screw ring. In most cases the associated switching devices possess several sets of fixed contact carriers and contact bridges, working in conjunction with the latter, which are equipped with their own restoring spring elements and are actuated by means of the plunger. Finally, connecting devices such as, for example, connector pins, for the electric lines are provided at the switching device.
The constantly necessary structural separation of a control-key switch into an actuator on the one hand, and a switching device on the other hand, raises the problem of connecting these two parts in an appropriate manner. The requirement exists for a safeguard against twisting which also resists shaking stresses which can occur, and for an adequate safeguard against pulling back since the latter must accommodate the actuating forces of the plunger and the considerably greater forces arising when axial plugs are pulled off.
Securing devices are known in the form of tiltable or displaceable latches which are actuated by means of a screwdriver and which are arranged in the region of the neck, plugged onto the actuator, of the switching device. These securing latches necessitate a considerable production effort and they proved to be unwieldy in operating since the insertion opening for the screwdriver, relative to the connecting side of the switching devices, is relatively deep and, with densely packed switching devices, cannot be inspected, but is in any case badly illuminated and additionally shaded by the connecting lines.
In addition, for connecting the parts of a control-key switch, plug arrangements are known in the manner of a bayonet lock, which are latched in the closed state. These have the disadvantage that for connecting and releasing the lock, due to the rotating catch, a relatively great angle of rotation is required which is not available with switching devices which are arranged closely together. In addition, it is considered as an impediment during installation that the switching devices must first be inserted in a difficult to find oblique position and must then be rotated into the final position.